This invention relates to a copying device for forming images using either thermodeveloping photosensitive materials or color photosensitive materials.
Conventionally, an electrophotographic method, ink jet method or the like is used to copy a color original.
In the electrophotographic method, a color image which has been fixed by heat or the like generally is reproduced after exposing the colored original using blue, green and red color-separating filters to form electrical latent images on a photosensitive drum that is electrostatically charged in response to the original, then developing the exposed color original using color toners of various colors such as yellow, magenta or cyan in sequence with the color-separated latent images and transferring the developed image onto a single recording paper by matching and overlaying color toner images with each of the color toners. However, placing one toner image on another a number of times causes color drift causing poorer image quality.
On the other hand, with the ink jet method, the colors of the color original are separated by color filters or the like and a value corresponding to the strength of the color is stored in memory. Following this, the color image is reproduced by ejecting ink from various color nozzles in accordance with the content of the memory. Unfortunately, ink-jet recording takes a long time to copy an image.
On the other hand, devices for copying desired color originals using silver halide color-sensitive materials are known. For example, the color copying device with is marketed under the trade name "Cibachrome color copy CC-001" (made by the Ciba Geigy Co. Ltd.) is a copying device which reproduces color images using color-sensitive materials of the so-called silver dye bleach (SDB) method type in which photosensitive silver halides and azo dyes are combined. Copying devices using color-sensitive materials have the advantage that it is possible to reproduce color images of high image quality in a single exposure without creating problems such as the need for a memory to record image data, as in the ink jet method, or color discrepancies which arise from overlaying toner images several times, as in the electrophotographic method.
Normally, in the just-mentioned copying devices, a color positive is used as the original document and color-sensitive reversal materials with which a color positive image is obtained from a color positive original are used as the multi-layer color-sensitive materials.
With multi-layer color-sensitive materials composed of photosensitive silver halide emulsion layers, the color image generally is formed by exposing the original and then passing it through an alkaline development process, but in the case of color-sensitive reversal materials the color positive image is obtained after passing the original through a complicated process involving exposure, then through a stage in which the exposed portions of the silver halide emulsion layers are subjected to black and white development, a stage in which the unexposed portions of the silver halide emulsion layers are exposed, a stage in which the unexposed portions of the silver halide emulsion layers which have then been exposed are subjected to color development processing, and a stage in which bleach-fixing is carried out in order to remove the silver image which forms as a result of the development processing. Furthermore, even when obtaining color images from the abovementioned SDB color-sensitive materials, there will normally be a need for a complicated process requiring at least 3 stages.
As mentioned above, with the electrophotographic method and the ink jet method, it is necessary to reproduce the color image by the color separation of the color original, and therefore there is a great need for at least three exposures and a memory to store the image data. Also, with the electrophotographic method, there is a reduction in image quality because of color discrepancy and the like. With the ink jet method, it takes time to form the copy image. Furthermore, with copying devices which use color-sensitive materials, the development processing stages after exposure are complicated. There is also a need for skill in the control of the development solutions. Also, the devices themselves are large, and their production costs are high. At the same time, the space occupied by machines is further increasing with advances in office automation, and so a reduction in machine size is becoming an essential requirement.